# [LeetCode 104. Maximum Depth of Binary Tree]
###### tags: `Leetcode`
* 題目
Given the root of a binary tree, return its maximum depth.

A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
* 解法
* 判斷左右子樹哪邊比較深
1. 把比較深的那邊+1然後在return
2. fmax(double, double)這個可以比較兩參數的大小，並回傳大的那個
* 停止條件
1. 當丟進來的tree是null，表示到最底部了

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */


int maxDepth(struct TreeNode* root){
    if(!root)
        return 0;
    return 1+fmax(maxDepth(root->left),maxDepth(root->right));
}